Polyolefin Alloys

Polycarbonate can be blended with polyethylene (PE). Bloiding PC with PE has found many uses with a combination of a high level of heat resistance and dimensional stability as well as noncorrosive properties and ease of moldabihty. It is deficient in its tendency to craze and crack under the effects of contact with organic solvents such as gasoline. The failure mechanism of a crazed PC would be brittle fracture ratha- than ductile fracture. Blending PC with low density polyethylene (LDPE) and with linear low density polyethylene (LLDPE) or with ethylene propylene diene monomer (EPDM) rubbo improves the chemical resistance of the product to solvents. 

Dow Chemical claims a patent on a blend [11] with a decreased tendency toward delamination, which exhibits a desirable balance of properties, a high level of impact resistance, solvent resistance, and processability. The product can be blown into films, spun into fibers, extruded into sheets, formed into multilayer laminates, and molded into any desired shape and can be used in data storage apparatus, appliance and instrument housings, motor vehicle body panels, and other parts and components for use in electrical, automotive, and electronic industries. 

The impact toughness and stiffness of polypropylene has important practical significance in extending its applications. For particulate-filled polypropylene (PP) 

The major theories used to interpret the toughening mechanisms of rubber-modified PP are multiple-crazing, damage competition, shear yielding theories, and microvoid and cavitation mechanisms. The rubber particles in a PP matrix have to be uniform in size, and the interfacial adhesion and morphological structure between the matrix and filler have to be excellent. 

RIP- and ROP-fllled brittle polymers toughen by a mechanism of nonelastic toughening. Studies on toughening mechanisms for PP-rubber blends are divided into 

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Polyolefin alloys Plascoat Systems Ltd. has developed a range of polyolefin alloys in its Performance Polymer Alloy (PPA) range. The exact compositions of these are secret. These products have been tailor-made to meet the needs of specific markets, e.g. 

Wallace J.G., A fabrication guide to processing MPRs and polyolefin alloys, Elastomerics, 120, 25, 1988. 

Cecchin, G., In Situ Polyolefin Alloys , Macromol. Symp., 78, 213-228 (1994). 

DeNicola, A., Hivalloy Resin Technology Reactor Produced Polyolefin Alloys, 2nd Annual North America Symposium on Recent Advances in Polymer Blends Alloys, Hilton Head, S.C. (1994). 

A variety of specialty polyolefins and polyolefin alloys can now be made directly in the reactor taking advantage f the new technology. Examples are the catalloy materials from Himont, which are polyolefin alloys made by synthesis and not by the conventional route of compounding. Hivalloy is a polypropylene/polystyrene alloy made by synthesis and combines the properties of both crystalline and amorphous engineering polymers. Such materials could challenge the established positions of several thermoplastic elastomers. 

We call this the "Reactor Granule" technology, and it represents a revolution in the development of "Ziegler-Natta" olefin polymerization. This "Reactor Granule" becomes a micropolyolefin production plant in which polyolefin alloys and blends are formed directly from the monomers. ... 

Variation of the monomer content and process parameters produces polyolefin alloys with an extremely wide range of potential properties. 

L.A. Utracki, Polyolefin alloys and blends. Makromol. Chem. Macromol. Symp. 118, 335-345... 

Hostalloy 731 Polyolefin alloy, with high abrasion resistance Hoechst Celanese Corp. 

RxLoy Polyolefin alloys for medical applicatirais Ferro Corp. 

D Chundry, S Edge, B Maclver, J Vaughn. Polyolefin alloys, blends and compounds. Plastics Formulating Compounding 2 18-24, 1996. 

Optum, Specialty polyolefin alloy resins, Ferro Corp., Filled Reinforced Plastics Div. 

The family of elastomers known as thermoplastic elastomers (TPEs) are based on crosslinked polyolefin alloys and are compounded with common... 

Using MgCl2-based catalysts for PP developed by Montedison it is possible to achieve control of the 3D structure of the catalyst particle and, as a result, of the obtained polymers. Such a polymer architecture control allows synthesis of new materials with improved properties like heteroplastic olefin copolymers, polyolefin alloys (Catalloy), and polyolefin alloys with non-olefinic polymers, which Montell has called Hivalloy. 

The research on reactor granule technology has opened up new possibilities in the field of polyolefin alloys. The Catalloy process allows unique reactor-made polymeric compositions endowed with properties no longer limited by mechanical considerations. 

METALLOCENE-BASED POLYOLEFIN ALLOYS, BLENDS AND COMPOUNDS... 

Metallocene-based polyolefin alloys, blends and compounds, an emerging class of novel plastic products, offer an unique combination of performance properties. In polymer blending and/or alloying, often dissimilar polymers are physically mixed (com-patibilized) and/or chemically reacted (reactive extrusion processing). 

The speciality polyolefin alloys are soft and flexible, halogen-free and plasticizer-free, good contact clarity, sterilizable, heat or radiofrequency sealable, good barrier properties, excellent chemical or solvent resistance, comply wit USP class VI, environmentally safe for disposition, ease of fabrication, and cost effective. Rxloy products, developed by Ferro Corporation, find medical applications in fluid administration, prefilled containers, blood bags, flexible containers, urine collection bags, and dry bags. These applications are from Rxloy FFS (form/fill/seal) and RF (radio fre-... 

Thermoplastic Elastomers (TPE) are classes of heterophasic polymers, characterized by thermo-reversible interaction among the polymeric chains. The new polymeric materials that are considered to produce easy recyclable automotive systems, can be defined as a sort of a new generation of Olefinic Thermoplastic Elastomers (TPO), belonging to a broad family of polyolefinic alloys that can now be produced directly dining the polymerization phase. These completely new materials, resulting from advanced research and development carried out by HIMONT, can be tailored in order to meet different requirements of most of car apphcations. The basic partly finished components suitable for the constructions of the main automotive composite structru-es will be described. 

It is the development of this granular polymer particle that has allowed production of unique, reactor made polyolefin alloys and blends without melt compounding. 

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